The solid electrolyte material includes Li, Ti, Zr, and F.

The production method of the present disclosure includes: heat-treating a material mixture containing LiA, YB.sub.3, GdC.sub.3, and CaD.sub.2 in an inert gas atmosphere. A, B, C, and D are each independently at least one selected from the group consisting of F, Cl, Br, and I. In the heat-treating, the material mixture is heat-treated at higher than or equal to 200° C. and lower than or equal to 700° C.

The solid electrolyte material of the present disclosure includes Li, Ca, Y, Sm, X, and O, where Xis at least one selected from the group consisting of F, Cl, Br, and I; and the molar ratio of O to the sum of Y and Sm in a surface area of the solid electrolyte material is higher than the molar ratio of O to the sum of Y and Sm in the entire solid electrolyte material.

The solid electrolyte material of the present disclosure is made of Li, Ca, Y, Gd, X, and O, where X is at least one selected from the group consisting of F, Cl, Br, and I; and the molar ratio of O to the sum of Y and Gd is greater than O and 0.51 or less.

A solid electrolyte (10) of the present disclosure includes porous silica (11) having a plurality of pores (12) interconnected mutually and an electrolyte (13) coating inner surfaces of the plurality of pores (12). The electrolyte (13) includes 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide represented by EMI-TFSI and a lithium salt dissolved in the EMI-TFSI. A molar ratio of the EMI-TFSI to the porous silica (11) is larger than 1.5 and less than 2.0.

A solid electrolyte composition includes: an inorganic solid electrolyte; binder particles having an average particle size of 1 nm to 10 μm; and a dispersion medium, in which the binder particles include a polymer that includes a component derived from a polymerizable compound having a molecular weight of lower than 1,000, and the component includes at least one of an aliphatic hydrocarbon chain to which 10 or more carbon atoms are bonded or a siloxane structure as a side chain of the polymer. The solid electrolyte composition is used in the sheet for an all-solid state secondary battery, the electrode sheet for an all-solid state secondary battery, the all-solid state secondary battery, the method of manufacturing a sheet for an all-solid state secondary battery, and the method of manufacturing an all-solid state secondary battery.

A solid electrolyte material contains Li, M, and X. M is at least one selected from metallic elements, and X is at least one selected from the group consisting of Cl, Br, and I. A plurality of atoms of X form a sublattice having a closest packed structure. An average distance between two adjacent atoms of X among the plurality of atoms of X is 1.8% or more larger than a distance between two adjacent atoms of X in a rock-salt structure composed only of Li and X.

A composite polymer electrolyte membrane comprising a nanofiber sheet having a basis weight of 1.5 g/m.sup.2 or more and 4.0 g/m.sup.2 or less, and a proton-conducting polymer, the electrolyte membrane having a sheet shape in which the proton-conducting polymer and the nanofiber sheet are combined, and having an average coefficient of linear expansion of 300 ppm/K or less from 20° C. to 120° C. in an in-plane direction of the sheet shape.

Electrodes containing lithium phosphate derivative materials and batteries with such electrodes are provided. The lithium phosphate derivative compounds contain an anionic framework capable of conducting lithium ions and have an activation energy from 0.2 to 0.45 eV and conductivities from 0.01 to 10 mS/cm at 300K. Materials of specific formulae are provided and methods to alter the composite materials with inclusion of aliovalent ions shown.

According to the present invention, there are provided a composite body that enables the formation of a lithium ion conductor that exhibits good lithium ion conductivity by a pressurization treatment without sintering at a high temperature (about 1,000° C.) while using a lithium-containing oxide having excellent safety and stability, as well as a lithium ion conductor, an all-solid state lithium ion secondary battery, an electrode sheet for an all-solid state lithium ion secondary battery, and lithium tetraborate. The composite body according to the embodiment of the present invention contains a lithium compound having a lithium ion conductivity of 1.0×10.sup.−6 S/cm or more at 25° C. and lithium tetraborate that satisfies the following requirement 1.

The requirement 1: In a reduced two-body distribution function G(r) obtained from an X-ray total scattering measurement of the lithium tetraborate, a first peak in which a peak top is located in a range where r is 1.43±0.2 Å and a second peak in which a peak top is located in a range where r is 2.40±0.2 Å are present, G(r) of the peak top of the first peak and G(r) of the peak top of the second peak indicate more than 1.0, and an absolute value of G(r) is less than 1.0 in a range where r is more than 5 Å and 10 Å or less.